Concrete structure with butt spliced compression and tension reinforcement



Sept. l2, 967 F. D. REILAND 3,340,664

CONCRETE STRUCTURE wTTE BUTT SPEICED COMPEESSICN AND TENSION REINFORCEMENT vFiled April 23, 1964 4 Sheets-Sheet l INVENTOR.

Sept. l2, F. D, RElLAND 3,340,664

CONCRETE STRUCTURE WITH BUTT SPLICED COMPRESSION AND TENSION REINFORCEMENT Filed April 25, 1964 4 Sheets-Sheet 2 Sept Z, 1967 F. D. REILAND 3,340,664

CONCRETE STRUCTURE WITH BUTT SPLICED COMPRESSION AND TENSION REINFORCEMENT Filed April 23, 1964 4 Sheets-Sheet 3 I NVENTOR.

F. D` E|LAND 3,340,664

BUTT SPLICED COMPRESSION AND TENSION REINFORCEMENT 4 Sheets-Sheet 4.

Sept. 12, i967 CONCRETE STRUCTURE WI Filed April 23, 1964 United States Patent O CONCRETE STRUCTURE WITH BUTT SPLICED COMPRESSION AND TEN- SION REINFORCEMENT Frank D. Reiland, Chicago, Ill., assignor to Gateway Erectors, Inc., Chicago, Ill., a corporation of Delaware Filed Apr. 23, 1964, Ser. No. 362,066 The portion of the term of the patent subsequent to Apr. 12, 1983, has been disclamed 7 Claims. (Cl. 52-648) The present invention relates to improvements in reinforced concrete stru-ctures of the general class in which the reinforcement thereof comprises conventionally deformed reinforcing bars spliced together in end-to-end relation and embedded in the concrete.

The principal' object of the invention is to provide a reinforced concrete structure of `the above class in which the several elements of the reinforcement for the concrete are so constructed and arranged as to provide an irnproved cooperative relation with each other and with the concrete body and lthereby provide the concrete structure in the region of the spliced ends of the bars with a strength capacity for supporting compression and for resisting tensional stresses, comparable to the strength capacity existing at any other location in the concrete structure.

Another object is to provide, in a reinforced concrete structure of the above class, an improved sleeve type clamp for applying a wrap-around constricting pressure across abutted end portions of a pair of primary reinforcing bars to force them into axial alignment and which include auxiliary reinforcing means interposed between the sleeve element of the clamp and the primary reinforcing bars being spliced and serving to increase the bonded and the interlocking engagement of the yconcrete with the primary reinforcing bars and the several elements of the clamp structure.

Another object is to provide, in a reinforced concrete structure of the above character, wherein the auxiliary Areinforcing elements of the splicing clamp, preferably though not necessarily reinforcing bars provided with conventionally deformed perimeters, cooperate with the deformations on the primary reinforcing bars and with the surrounding sleeve element of the clamp to increase the metallic areas for bonding engagement with the concrete and which cooperate with the concrete both within the sleeve and beyond its opposite ends to provide multiple locking keys of concrete for transmitting lcompressive and tensional thrusts from one primary reinforcing bar to another. That is, the invention affords va combination cast and clamp joint, the interlocking keys of concrete being formed by admission of the concrete mass into the interior of the clamp sleeve.

A further object is to provide a splice clamp of the above construction in which the auxiliary reinforcing elements in the clamp assembly are readily interchangeable with others of `suitable length to provide the splice structure with appropriate strength capacity for withstanding potential stresses -at different splice locations in the reinforcement structure.

The invention is illustrated in the accompanying drawings wherein:

FIG. 1 s-a side view in elevation of a concrete body reinforced with primary reinforcing bars embedded therein in endwise abutting relation and connected together by splice means constructed according to the present invention to cooperate with the concrete to resist compressive and tensional stresses of different potentials at the locations of the several splices.

FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. l;

Patented Sept. 12, 1967 ice FIG. 2a is a fragmentary cross-section taken on line Za-Za or FIG. 1;

FIG. 3 is a cross-section taken on line 3-3 lof FIG. l;

FIG. 4 is an exploded View showing in perspective the several components of a butt splice connection according to lone preferred embodiment of the invention;

FIG. 5 is a View in perspective of the several parts of FIG. 4 in their assembled relation;

FIG. 6 is a cross-section taken on lines 6--6 of FIG. 5;

FIG. 7 is a longitudinal section taken substantially on lines 7-7 of FIGS. l and 8;

FIG. 8 is a cross-sectional view taken on line 8-8 of FIG. 7;

FIG. 9 is an exploded view similar to FIG. 4 but including additional parts of an improved redu-cer sleeve structure to adapt the splice structure of FIGS. 4 and 5 to primary reinforcing bars of different standard diameters.

FIG. l0 is a longitudinal section taken on lines 10-10 of FIGS. 1 and ll;

FIG. 11 is a cross-section taken on line 11-11 of FIGS. l0; and

FIG. 12 is a fragmentary sectional View similar to FIG. 7 illustrating in exaggerated proportion, transverse yielding of the splice structure to accommodate tolerance variations in the diameters of abutted reinforcing bars.

Referring rst to FIGS. l to 8, inclusive, of the drawings: 10 designates a concrete body reinforced in accordance with the present invention. The concerte body may be of any form in which conventional reinforcing bars are spliced together and embedded in the concrete to provide the desired reinforcement. However, for the purpose of illustration, but not as a limitationthe body 10 is shown herein as a portion of the frame of a multiple story building.

The building frame shown may be described .briey as comprising foundation piers 11-11a, vertical columns 12-12a supported on the piers, and horizontal girders 13-13a for connecting the upper ends of the columns 12-12a and other verticals (not shown) in the structure.

The foundation piers 11-11a and the columns 12-12a are subjected principally to compressive stresses because of the compression load imposed thereon. However there are some recurrent tensional stresses in the Icolumns from time to time to be overcome by the reinforcement embedded in the concrete. Such tensional forces may result from pronounced wind pressures or other disturbing influences, all of which are considered in the design of the improved clamp structure of the present invention.

The horizontal girders 13-13a and their associated beams (not shown) are subjected principally to tensional stresses incident to their own weight land any additional floor load imposed thereon. These tensional stresses are more pronounced at locations below the horizontal center (neutral axis) of the horizontal members. Consequently, the metallic reinforcements for `concrete girders and beams are usually embedded in the concrete intermediate their neutral axes and their bottom faces.

Each column 12 or 12a extends from its associated foundation pier 11 or 11a to a girder 13 or 13a associated with an upper floor. However inasmuch as the columns 12-12a are shown broken away at 14-14a and in View also of the fact that the reinforcing bars embedded in the columns are normally of lengths suflicient to extend beyond the third floor, the girders 13-13a may be regarded as being associated with the second or third oors of the building.

Referring now to the reinforcements associated with the pier 11 and the column 12. These reinforcements v comprise a suitable number of reinforcing bars to provide the required reinforcement of the concrete. In the construction shown herein there are four pairs of bars arranged vertically in end-to-end relation. The lower group of bars are designated 15, 16, 17 and 18 (see FIGS. 1, 2 and 2a) and are embedded in the foundation pier 11. The length of these bars will depend upon the depth of the pier and the amount of reinforcement required. The upper ends of these bars extend different distances above the pier 11 and are butt spliced to the lower end portions of reinforcing bars 19, 20, 21 and 22 (see FIGS. 1 and 2) by means of identical splice structures designated 23, 24, 25 and 26, the structural details of which are shown in FIGS. 4 to 8, inclusive. The bars 20, 21 and 22 are of suflicient length to extend above the upper floor associated with the girders 13, 13a and serve as dowels to which additional bars (not shown) of the same or of smaller diameters may be spliced to extend the height of the building.

For the purpose of illustrating bars of different standard diameters spliced together, the bar 19 is stopped short of the girder 13 and is spliced to a bar 27 of smaller diameter by means of a slightly modified splice structure designated 28 and shown in detail in FIGS. 9, 10 and 11 of the drawings.

Before embedment of the vertical reinforcing bars in the pier 11 and column 13, suitable ties 29 are secured to the bars at spaced locations to maintain the bars in parallel relation.

The reinforcements embedded in the pier 11a and in the column 12a are substantially the same as the reinforcements for pier 11 and column 12. The only difference in construction is that the bar 19a is of full length and extends above the floor level of girders 13 and 13a. Therefore, for the sake of brevity, the reinforcements embedded in the foundation pier 11a and in the column 12a are indicated by the same reference numerals applied to the reinforcements in pier 11 and column 12 plus the letter a.

The vertical members of a building frame are subjected principally to compression loads such as indicated by the heavy arrows 30 and are reinforced accordingly to resist these primary stresses and such secondary tensional stresses as may develop from strong Wind pressures and other transitory influences tending to momentarily sway or deflect the building structure from its normal position. The horizontal members of the frame structure of a building, for example the girders 13, 13a are subjected to both compressive and tensional stresses such as represented by the heavy arrows designated 31 and 32. However, since the tensional stresses in a girder present the greater problem, the girders shown herein are reinforced by means of reinforcing bars 33, 34 and 35 extending lengthwise of the girder near the bottom face thereof since it is the region of the girder below its horizontal center that is subjected to the greater tension. The bar 33 is of sufficient length to extend the entire length of the girder 13, but the bars 34 and 35 are butt spliced together by means of a splice structure 36. The structure of this splice may be identical in some situations to that of splice 23. However in other situations where greater tensile strength is required, auxiliary reinforcements designated 36 in FIG. 1 are formed of greater length than similar reinforcements in the other splice structures herein shown 'and thereby provide greater area for bonded contact with the concrete.

Referring now to the details of the compression clamp structures 23, 24, 25 and 26: Inasmuch as these several clamps are of identical construction, it will be suflicient to describe the clamp 23 for butt splicing together the Vertical reinforcing -bars and 19. For this purpose reference is made to FIGS. 4 to 8, inclusive, of the drawings. The bars 15 and 19 constitute primary reinforcing bars and like all other primary reinforcing bars herein shown are provided with perimeters defined by conventional deformations. These deformations as shown comprise a series of outwardly projecting ribs 37, 38 and 39 which provide a firmly bonded and interlocked engagement in the concrete. The deformations 37-38 extend lengthwise of the bars on opposite sides thereof (FIGS. 4 and 6) and the deformations 39 are spaced apart transverse ribs.

The splice structures, for example the structure 23 for splicing the primary vertical reinforcing bars 15-19 `comprise a split sleeve 41 for embracing the abutted ends of the said bars 15-19, auxiliary reinforcing bars embedded in the concrete in close relation to the sleeve and bars 15-19 and comprising one or more deformed reinforcing bars 42 of smaller diameter. When the sleeve 41 is of angular cross-section, the bars 42 are interposed between the sleeve and the -bars 15-19 to extend lengthwise thereof across the adjacent ends of the bars, and a wedge member 43 engaging portions of the sleeve to contract its diameter and thereby exert constricting pressure against the bars 42 to clamp them against the bars 15-19. The deformations of the auxiliary reinforcing bars include ribs 42 which project laterally therefrom in close cooperative relation with the deformations on the bars 15- 19 to increase the bonded interlocking contact therewith.

The sleeve may be of any desired cross-sectional contour. In the present embodiment the sleeve element 41 is rectangular in cross-section and an auxiliary reinforcing means, for example a deformed bar 42, is positioned in each corner portion of the sleeve to overlap the abutted ends of the primary reinforcing bars for a selected distance at opposite side of their end faces 44-45. In some installations, for example when the splice structure is utilized as a compression splice the auxiliary reinforcing bars 42 may extend only a short distance beyond the ends o-f the sleeve element 41 as shown in full lines in FIG. 5, but when the splice structure is utilized primarily to provide increased yield strength and thereby increase the resistance at the splice to tensional stresses, for example as required by the position of the splice 36 shown in FIG. l, the auxiliary reinforcing bars 42 may be readily replaced by the longer bars shown at 36 in FIG. l and as indicated in dotted lines of 36" in FIG. 5.

One side of the sleeve element is split as indicated at 46 and the opposite edges along the split are turned outwardly and laterally to form hook shaped wedge flanges 47 which diverge from each other from top to the bottom of the sleeve and provide wedges. A wedge member 43 is provided wtih inturned diverging wedge shaped flanges 43--43 which interlock with the wedge flanges 47-47 on the sleeve 41. When the wedge flanges 43'-43 of the wedge member 43 are interlocked with the wedge flanges 47-47 of the sleeve, the wedge may be driven downwardly relative to the sleeve. This downward movement of the wedge contracts the diameter of the thin walled sleeve by drawing the flanges 47-47 toward each other. This contraction of the sleeve tensions all sides thereof and thereby applies constricting clamping pressure to the auxiliary reinforcing bars 42 to press them tightly against the perimeters of both bars 15-19. This constricting pressure being applied across the butted ends of the said bars 15-19, shifts the upper bar 19 laterally relative to the anchored bar 1S to effect axial alignment of the end portions of both bars 15-19 and maintains them in alignment both prior to and during the pouring of the concrete.

The sleeve 41 is not only suliciently thin and bendable to contract into gripping contact with the bars 42 lduring the movement of the wedge 43 to its normal operative position, but all of its side -Walls are subjected to circumferential tension. Inasmuch as the auxiliary reinforcing bars y42 have capacity for slight rolling movement on the perimeters of the bars 15-19, the bars 42 will automatically adjust themselves in the diretcions indicated lby the curved arrows in FIG. 6 to equalize the tensional stress on all side walls of the sleeve 41.

If the primary reinforcing bars 15-19 have identical diameters, the tensioning of the side walls of the sleeve 41 will be uniform throughout the length of the sleeve. However, if there should be slight variations in the diameters of the Iprimary reinforcing bars, for example as 1ndicated by the bars 15e and 19c in FIG. 12, that is to say a variation in the diameters within the allowable manu- Iacturers tolerance, the pressure exerted by the wedge 43 will impart greater yield or stretch to the end portion of the sleeve 41e` which embraces the bar 15C of larger diameter. Also the constricting pressure exerted by the other end of the sleeve 41C on the auxiliary bars 42C will I'bend these bars as indicated at 51 in said FIG. 12 so that they will bear rmly against the perimeter of the primary reinforcing bar 19e of smaller diameter.

The ultimate strength in compression of the reinforcement in the region of the spliced bar ends is equal to or greater than its strength at any other location in lthe structure, since the major portion of the compressive stresses are transmitted directly across the opposed end faces 44-45 of the primary reinforcing bars.

The primary reinforcing bars are therefore preferably, though not necessarily, provided with square cut ends so that the end faces will have full area contact. However, if the end faces of a bar, as they come from the mill,are substantially normal to the axis of the bar, yfor example as shown in FIG. 7, such bar may be used without additional treatment of its end faces. In such case, the adjacent ends of abutted bars are brought together as shown in FIG. 7 of the drawings and both bars are securely clamped together by means of the auxiliary reinforcing bars 42 and the clamp sleeve 41.

When the splice structure is in its proper position, the position of the bar end faces 44-45 may be observed through aligned inspection openings 52-53 formed in opposed side walls of the sleeve 41. These openings together with the open ends `54-55 of the sleeve, two groups of apertures 56-57 formed in the opposed side walls and in the rear wall of the sleeve, and apertures 58 formed in the wedge 43 serve to expedite the llow of concrete grout into the sleeve 41 during the lforming of the main concrete body 10. The concrete grout completely iills the sleeve 41 and surrounds both bars 15-19 and each auxiliary reinforcing bar 42. The same openings in the sleeve and wedge serve as flow passageways for delivering concrete grout into the space between the end faces 44- 45 to form a non-compressible body 60 therein. The concrete bed 60 serves to transmit compressive thrusts from one primary reinforcing bar (l5-19) to the other as effectively as a direct metallic contact of the end faces 44- 45 of the bars. The body of concerte 61 within the sleeve serves to provide a irm bonded connection between the primary reinforcing bars 15-19, the auxiliary bars 42,

and the inner faces of the walls of the sleeve 41, atfording a combined cast and clamp joint.

The four auxiliary reinforcing bars 42 have a total cross-sectional area equal to or slightly greater than the cross-sectional area of a single primary reinforcing bar 15 or 19. Consequently, the total external surface per linear inch of the auxiliary bars 42, for bonding with the concrete body 61, is substantially greater than that of either primary reinforcing bar 15 or 19. For a specic illustration of the a'bove, it can be assumed that the primary reinforcing bars 15-19 are No. 18 bars. Therefore according to present standard specifications each bar has a diameter of 2.257", a cross-sectional area of 4.00" and a perimeter area per linear inch of 7.09 square inches. Assuming that the auxiliary reinforcing bars 42 are the No. 9 size, each will have a diameter of 1.128, a cross-sectional area of 1.00", and a perimeter area per linear inch of 3.544. Therefore, the total perimeter area Iper linear inch of the four auxiliary reinforcing bars 42 for bonded contact with the concrete is 13.176 square inches as compared with a peripheral area of 7.09l for the No. 18 bar.

In addition the greater bonding area per linear inch of the smaller bars 42 and the transverse deformation ribs 42 of the bars 42 constitute abutments positioned in opposition to the transverse ribs 39 of the primary reinforcing bars 15-19. The small bodies 63 (see FIG. 7) of concrete which intervene between the ribs 39 of the primary reinforcing bars and the transverse ribs 42 of the auxiliary reinforcing bars constitute locking keys which interlock both primary reinforcing bars with each auxiliary reinforced bar 42 of the splice structure.

The said locking keys 63 function during the presence of both compressive and tensional stresses on the splice structure 23 and/or the splice structure 36, shown in FIG. 1, to transmit these stresses from one primary reinforcing bar to the other through the auxiliary bars 42. For example, compressive stresses in the primary reinforcing bar 19 are transmitted in part from ribs 39 of bar 19 to the ribs 42' on the auxiliary reinforcing ba-r 42 in the rdirection of the inwardly pointing arrows 64 (see FIG. 7), thence through the bars 42 through the locking keys 63' in the direction of inwardly pointing arrows 64 to a rib 39 on the primary reinforcing bar 15.

When the splice 23 (FIG. 1) is subjected to tensional stresses the tensional force is transmitted from one to the other of the primary reinforcing lbars 15 or 19 as follows. Assuming that the tension originates in the bar 19, it will be transmitted from the lateral ribs 39 thereof through the concrete locking keys 63 in the direction of the outwardly pointing arrows 65 to a Igroup of ribs 42 on the bars 42 and thence through bars 42 to a concrete locking key 63 through which the tensional force is transmitted in the direction indicated by the outwardly pointing arrows 65.

Referring again to the two groups of apertures 56 and 57: The apertures 56 are formed in the position of the sleeve 41 which embraces the splice end of bar 19 and the apertures 57 are formed in the portion of the sleeve 41 embracing the splice end of the bar 15. The perimeters 66 of the apertures 56 provide abutment faces positioned in opposition to the deformation ribs 39 on the splice ends of bars 15-19 within the sleeve 41. The bodies of concrete 68 interventing between the deformation ribs 39 of bar 19 and the abutment face 66 of apertures 56 constitute locking keys which transmit compressive stresses from the bar 19 to the sleeve 41 in the direction of the inwardly pointing arrows 69 (see FIG. 7). These stres-ses are then transferred from an abutment face 67 of the sleeve 41 to the |bar 15 through the concrete locking keys 68' in the ydirection'of the inwardly pointing arrows l69' (see FIG. 7) to the -bar 15.

Assuming now that the splice structure 23 (FIGS. 1 and 7) is subjected to tensional stresses originating in the primary reinforcing bar 19: Such stresses are transf mitted from the bar 19 through the concrete locking keys 68 to the perimeter surface 66 of the apertures 56 in the direction indicated by the outwardly pointing arrows 70, thence through the sleeve 41 to the perimeter surfaces `67 and thence through conc-rete interlocking keys 68 in the direction indicated by the outwardly pointing arrows 70 to a transverse rib 39 on the bar 15. If the tensional stress originates in the bar 15, it is transmitted to bar 19 in the same manner, but in a reverse direction.

The transmission of compressive and tensional stresses apply also to the portions of the auxiliary reinforcement Ibars 42 which project beyond the ends of the sleeve 41. Consequently, a splice structure if located in a region where tensional stresses are more Ipronounced than in other locations, for example in a gir-der 13 at the location of the splice structure 36, longer auxiliary bars 36 may -be used as indicated in FIG. 1. The longer bars will provide the splice structure with added strength for transmitting the prevailing stresses from one to the other bars 15-19 or 34-35 at the special location of the splice.

Referring now to the modified splice structure 28 (FIGS. 1, 9, 10 and 11): The construction of this modified splice is for the most part identical with the splice 23 disclosed in FIGS. 4 through 8, inclusive. The only structural distinction present in the modification shown in FIGS. 9, 10 and l1 is that it includes a `special reducer sleeve structure, whereby reinforcing bars of various diameters may be spliced together. Therefore the detailed description of FIGS. 9, l and 11 will be confined to the distinguishing features. The other structural embodiments of FIGS. 9, l0 and l1 which are also present in FIGS. 4 through 8 are identified by the same reference numerals with the addition of the latter b.

The reducer sleeve structure shown herein comprises a plurality of semi-cylindrical sleeve sections 71, 72, 73 and 74 arranged in pairs Iand nested about the splice end `of the bar 27. The nested sleeve sections are sufficient in number and thickness to accurately compensate for the difference in the diameters of the bars 12b and 27. The vertical edges of the sleeve sections are spaced apart slightly as indicated `at 75 in FIG. 11 so as to permit some fiexing of the sleeve sections in the event of a tolerance Variation in the diameter or periphery contour of the smaller bar 27. When the reducer sleeve sections are in their proper positions, the perimeters of the outer sections align with the perimeter of the larger bar 12b and provide a bearing for the auxiliary reinforcing bars 42b.

All of the nested sleeve sections are provided with registering apertures 76 to provide passageways to expedite the flow of concrete through the reducer sleeve sections. This grout acquires a firm bond with the bars 27 and 42b. Also the portion of the grout located in the registering apertures 76 constiute locking keys which engage the transverse ri-bs 77 on the bar 27 and the ribs 42b on auxiliary reinforcing bars 4217 and thereby resist movement of the bar 27 relative to the bar 4211. Similar concrete locking keys 78 (see FIG. l0) exist between the transverse deformation ribs 42b on bars 42h and the perimeter surfaces 6617 of the apertures 56b formed in the w-a-lls of the sleeve 41h. In other respects the functioning of the embodiment shown in FIGS. 9, and ll is the same as described in connection with FIGS. 4 through 8, inclusive.

While the invention is shown and described herein in connection with certain preferred embodiments, it will be obvious that the principles of the present invention herein disclosed may =be embodied in other splice structures without departing from the spirit of the present invention. Therefore it is to be understood that all such Variations which come within the terms of the appended claims are contemplated as apart of the present invention.

1. In a metal-reinforced concrete body having an elongated primary metal reinforcement bar extending therethrou-gh, said primary reinforcement bar being of the kind having multiple projecting deformation ribs spaced apart lengthwise thereof and defining intervening channels, a combination clamp and cast joint structure joining two end-abutting segments of said primary reinforcement bar within said body, said joint structure comprising a plurality of individual elongated auxiliary metal reinforcement bars extending longitudinally of said primary reinforcement bar across the butt joint between said two segments, a constrictive clamp member comprising a relatively exible contractible sheet metal sleeve tightly encompassing an enclosing said auxiliary reinforcement bars and clamping said bars tightly against both segments of said primary reinforcement bar, and a concrete mass totally filling said sleeve and said channels and interlocking all -of said metal :members in an integral joint structure.

2. A combination clamp and cast joint structure according to claim 1 in which each of said auxiliary reinforcment bars is provided with multiple projecting deformation ribs spaced apart lengthwise thereof Iand defining intervening channels and in which said concrete mass fills said channels in said lauxiliary reinforcement bars, serving to -increase the bonded attachment of the primary and auxiliary reinforcement bars through the concrete.

3. A combination clamp and cast joint structure according to claim 2 in which said metal sleeve is provided with a plurality of apertures and in which said concrete mass extends through each of said apertures to interlock said joint structure with the encompassing concrete body.

4. Acornbination clamp and cast joint structure according to clai-m 3 in which said sleeve is of substantially regular polygonal cross sectional configuration and in which one of said auxiliary reinforcement vbars is located in each corner of the sleeve at the junction of two adjacent walls of the polygon.

5. A combination clamp land cast joint structure according to claim 3 in which said auxiliary reinforcement bars each extend along the primary reinforcement bar segments for substantial distances beyond the opposite ends of the contractible sleeve to yafford increased resistance to tensional stresses at the joint.

6. A combination clamp and cast joint structure according to claim 3 in which said segments of said primary reinforcement bar are of different standard diameters, said joint structure further comprising a reducer sleeve disposed in encompassing relation to the end portion of the primary reinforcement bars segment of smaller diameter with the outer surface of the reducer sleeve affording a bearing surface for said auxiliary reinforcement bars.

7. A combination clamp and cast joint structure according to claim 6 in which said reducer sleeve comprises a plurality of arcuate sleeve sections arranged in encompassing relation to said smaller diameter segment of said primary reinforcement bar Iand in which said reducer sleeve sections are each provided with a plurality of apertures filled by said concrete mass to interlock the cornplete joint structure in an integral unit.

References Cited UNITED STATES PATENTS 444,579 1/1891 Jackson 189--36 943,469 12/1909 Schade 52--726 1,035,816 8/1912 Allen 52-730 1,383,451 7/1921 Dalrymple 287-111 1,689,281 10/1928 Forssell 52-726 3,245,189 4/1966 Reiland 52-648 FOREIGN PATENTS 44,161 7/ 1927 Norway. 520,214 6/ 1921 France.

FRANK L. ABBOTT, Primary Examiner.

J. L. RIDGILL, Assistant Examiner. 

1. IN A METAL-REINFORCED CONCRETE BODY HAVING AN ELONGATED PRIMARY METAL REINFORCEMENT BAR EXTENDING THERETHROUGH, SAID PRIMARY REINFORCEMENT BAR BEING OF THE KIND HAVING MULTIPLE PROJECTING DEFORMATION RIBS SPACED APART LENGTHWISE THEREOF AND DEFINING INTERVENING CHANNELS, A COMBINATION CLAMP AND CAST JOINT STRUCTURE JOINING TWO END-ABUTTING SEGMENTS OF SAID PRIMARY REINFORCEMENT BAR WITHIN SAID BODY, SAID JOINT STRUCTURE COMPRISING A PLURALITY OF INDIVIDUAL ELONGATED AUXILIARY METAL REINFORCEMENT BARS EXTENDING LONGITUDINALLY OF SAID TWO REINFORCEMENT BAR ACROSS THE JOINT BETWEEN SAID TWO SEGMENTS, A CONSTRICTIVE CLAMP MEMBER COMPRISING A RELATIVELY FLEXIBLE CONTRACTIBLE SHEET METAL SLEEVE TIGHTLY ENCOMPASSING AN ENCLOSING SAID AUXILIARY REINFORCEMENT BARS AND CLAMPING SAID BARS TIGHTLY AGAINST BOTH SEGMENTS OF SAID PRIMARY REINFORCEMENT BAR, AND A CONCRETE MASS 